The growth of high-bandwidth services such as high-definition online video and cloud computing has posed a huge bandwidth challenge to an optical communications network. The optical communications network mainly includes three parts: a transport network, a switching network, and an access network. Because of technical limitations such as a switching speed and energy consumption, an electrical switch in the switching network cannot meet a demand for a huge switching throughput in a high bandwidth requirement. As an optical signal switching technology with low energy consumption and a high throughput, an all-optical switching technology will replace an electrical switching technology and become a main technology for the switching network in the future.
A core component for implementing the all-optical switching technology is an optical switch matrix. A type of optical switch matrix is based on silicon-based MEMS technology optical switches that have a hysteresis effect. An optical switch matrix of this type has advantages such as a high speed and a low insertion loss, and can meet an increasing data exchange requirement of the switching network. A basic unit of the optical switch matrix of this type is a 2×2 optical switch. The 2×2 optical switch includes cross waveguides and a movable waveguide. When the movable waveguide moves away from the cross waveguides, the optical switch is in an OFF state, and an optical signal keeps propagating directly through the cross waveguides. When the movable waveguide moves close to the cross waveguides, the optical switch is in an ON state, the cross waveguides and the movable waveguide form adiabatic couplers, and an optical signal is coupled from one waveguide to the other waveguide by using the adiabatic couplers.
The optical switch matrix usually has a crossbar topological structure. The crossbar topological structure is an optical switch matrix structure formed by connecting 2×2 optical switches together in a cross-bar manner. For example, for an n×n optical switch matrix, n2 optical switches are connected together in n rows and n columns, left ports of optical switches in a first column serve as input ports of the optical switch matrix, and lower ports of optical switches in an nth row serve as output ports of the optical switch matrix. When the optical switch matrix needs to switch an optical signal on an input port i to an output port j, it is required to switch an optical switch in an ith row and a jth column to the ON state, and switch other optical switches in the ith row and other optical switches in the jth column to the OFF state. For the n×n optical switch matrix of the crossbar topological structure, if n input ports and n output ports are all used, only n optical switches in the optical switch matrix are in the ON state, and the other optical switches are in the OFF state. Each optical switch has two electrodes, and a state of the optical switch is driven by a voltage difference (referred to as a drive voltage) between the two electrodes.
When a size of the optical switch matrix is small, electrodes of each optical switch may be connected to an external drive circuit for separate control. As input ports and output ports of the optical switch matrix increase in quantity, a quantity of optical switches in a crossbar topological structure increases exponentially. If electrodes of the optical switches are all connected to external drive circuits for separate control, there are a large quantity of chip pins, and packaging is highly difficult.
An existing solution is a serial control method, in which one electrode of all optical switches in each row is connected and extruded together in rows and the other electrode of all the optical switches in each row is connected and extruded together in columns. For the n×n optical switch matrix, a total quantity of electrodes extruded to edges of a chip is 2n. With such a connection, a voltage difference between two electrodes of the optical switch in the ith row and the jth column is a difference between a voltage of the ith row and a voltage of the jth column. However, due to the hysteresis effect of the optical switch, optical switches that need to be switched can only be controlled one by one in this solution. When a relatively large quantity of ports need to be switched, many optical switches need to be controlled, and this greatly prolongs a switching time of the optical switch matrix and reduces working efficiency of the optical switch matrix.